Question

1. Dùng định nghĩa hai phân thức bằng nhau chứng tỏ rằng :

a) x²y³/5 = 7x³y⁴/35xy
b) x³ - 4x/10-5x = -x²-2x/5
c)x + 2/ x-1 = (x+2)(x+1)/ x²-1
d) x² - x - 2/ x+1 = x² - 3x +2/ x-1
e) x³+8/ x²-2x+4 = x+2

Answer 1

bn làm đc câu này chưa vậy

Answer 2

a: \(\dfrac{7x^3y^4}{35xy}=\dfrac{7xy\cdot x^2y^3}{35xy}=\dfrac{x^2y^3}{5}\)

b: \(\dfrac{x^3-4x}{10-5x}=\dfrac{-x\left(x-2\right)\left(x+2\right)}{5\left(x-2\right)}=\dfrac{-x^2-2x}{5}\)

c: \(\dfrac{\left(x+2\right)\left(x+1\right)}{x^2-1}=\dfrac{\left(x+2\right)\left(x+1\right)}{\left(x-1\right)\left(x+1\right)}=\dfrac{x+2}{x-1}\)

d: \(\dfrac{x^2-x-2}{x+1}=\dfrac{\left(x-2\right)\left(x+1\right)}{x+1}=x-2=\dfrac{\left(x-2\right)\left(x-1\right)}{x-1}=\dfrac{x^2-3x+2}{x-1}\)

e: \(\dfrac{x^3+8}{x^2-2x+4}=\dfrac{\left(x+2\right)\left(x^2-2x+4\right)}{x^2-2x+4}=x+2\)